Adds an invert method to promises that returns a "inverted" promise that is resolved when the underlying deferred is rejected and rejected when the underlying deferred is resolved.

src/core.js

@@ -56,8 +56,16 @@ var jQuery = function( selector, context ) {
 	// The deferred used on DOM ready
 	readyList,
 
-	// Promise methods
+	// Promise methods (with equivalent for invert)
-	promiseMethods = "then done fail isResolved isRejected promise".split( " " ),
+	promiseMethods = {
+		then: 0, // will be overwritten for invert
+		done: "fail",
+		fail: "done",
+		isResolved: "isRejected",
+		isRejected: "isResolved",
+		promise: "invert",
+		invert: "promise"
+	},
 
 	// The ready event handler
 	DOMContentLoaded,
@@ -879,8 +887,9 @@ jQuery.extend({
 	Deferred: function( func ) {
 		var deferred = jQuery._Deferred(),
 			failDeferred = jQuery._Deferred(),
-			promise;
+			promise,
-		// Add errorDeferred methods, then and promise
+			invert;
+		// Add errorDeferred methods, then, promise and invert
 		jQuery.extend( deferred, {
 			then: function( doneCallbacks, failCallbacks ) {
 				deferred.done( doneCallbacks ).fail( failCallbacks );
@@ -892,18 +901,35 @@ jQuery.extend({
 			isRejected: failDeferred.isResolved,
 			// Get a promise for this deferred
 			// If obj is provided, the promise aspect is added to the object
-			promise: function( obj , i /* internal */ ) {
+			promise: function( obj ) {
 				if ( obj == null ) {
 					if ( promise ) {
 						return promise;
 					}
 					promise = obj = {};
 				}
-				i = promiseMethods.length;
+				for( var methodName in promiseMethods ) {
-				while( i-- ) {
+					obj[ methodName ] = deferred[ methodName ];
-					obj[ promiseMethods[ i ] ] = deferred[ promiseMethods[ i ] ];
 				}
 				return obj;
+			},
+			// Get the invert promise for this deferred
+			// If obj is provided, the invert promise aspect is added to the object
+			invert: function( obj ) {
+				if ( obj == null ) {
+					if ( invert ) {
+						return invert;
+					}
+					invert = obj = {};
+				}
+				for( var methodName in promiseMethods ) {
+					obj[ methodName ] = promiseMethods[ methodName ] && deferred[ promiseMethods[methodName] ];
+				}
+				obj.then = invert.then || function( doneCallbacks, failCallbacks ) {
+					deferred.done( failCallbacks ).fail( doneCallbacks );
+					return this;
+				};
+				return obj;
 			}
 		} );
 		// Make sure only one callback list will be used

test/unit/core.js

@@ -554,8 +554,8 @@ test("toArray()", function() {
 	expect(1);
 	same( jQuery("p").toArray(),
 		q("firstp","ap","sndp","en","sap","first"),
-		"Convert jQuery object to an Array" )
+		"Convert jQuery object to an Array" );
-})
+});
 
 test("get(Number)", function() {
 	expect(2);
@@ -567,7 +567,7 @@ test("get(-Number)",function() {
 	expect(2);
 	equals( jQuery("p").get(-1), document.getElementById("first"), "Get a single element with negative index" );
 	strictEqual( jQuery("#firstp").get(-2), undefined, "Try get with index negative index larger then elements count" );
-})
+});
 
 test("each(Function)", function() {
 	expect(1);
@@ -1009,7 +1009,7 @@ test("jQuery._Deferred()", function() {
 
 test("jQuery.Deferred()", function() {
 
-	expect( 10 );
+	expect( 20 );
 
 	jQuery.Deferred( function( defer ) {
 		strictEqual( this , defer , "Defer passed as this & first argument" );
@@ -1049,10 +1049,26 @@ test("jQuery.Deferred()", function() {
 		ok( true , "Error on reject (new)" );
 	});
 
+	strictEqual( jQuery.Deferred().resolve( "test" ).invert().then(null,function(value) {
+		strictEqual( value, "test", "Resolved deferred => then fail callback called" );
+	}).fail(function( value ) {
+		strictEqual( value, "test", "Resolved deferred => fail callback called" );
+	}).isRejected(), true, "Invert promise is rejected when deferred is resolved" );
+
+	strictEqual( jQuery.Deferred().reject( "test" ).invert().then(function(value) {
+		strictEqual( value, "test", "Rejected deferred => then done callback called" );
+	}).done(function( value ) {
+		strictEqual( value, "test", "Rejected deferred => done callback called" );
+	}).isResolved(), true, "Invert promise is resolved when deferred is rejected" );
+
 	var tmp = jQuery.Deferred();
 
 	strictEqual( tmp.promise() , tmp.promise() , "Test deferred always return same promise" );
+	strictEqual( tmp.invert() , tmp.invert() , "Test deferred always return same invert" );
 	strictEqual( tmp.promise() , tmp.promise().promise() , "Test deferred's promise always return same promise as deferred" );
+	strictEqual( tmp.promise() , tmp.invert().invert() , "Test deferred's promise is the same as double invert" );
+	strictEqual( tmp.invert() , tmp.invert().promise() , "Test deferred's invert always return same invert as deferred as a promise" );
+	strictEqual( tmp.invert() , tmp.promise().invert() , "Test deferred's promise always return same invert as deferred" );
 });
 
 test("jQuery.when()", function() {
@@ -1100,7 +1116,7 @@ test("jQuery.when()", function() {
 
 test("jQuery.when() - joined", function() {
 
-	expect(8);
+	expect(14);
 
 	jQuery.when( 1, 2, 3 ).done( function( a, b, c ) {
 		strictEqual( a , 1 , "Test first param is first resolved value - non-observables" );
@@ -1121,12 +1137,28 @@ test("jQuery.when() - joined", function() {
 		ok( false , "Test the created deferred was resolved - resolved observable");
 	});
 
+	jQuery.when( 1 , successDeferred.invert() , 3 ).fail( function( a, b, c ) {
+		strictEqual( a , 1 , "Test first param is first rejected value - resolved observable inverted" );
+		same( b , 2 , "Test second param is second rejected value - resolved observable inverted" );
+		strictEqual( c , 3 , "Test third param is third rejected value - resolved observable inverted" );
+	}).done( function() {
+		ok( false , "Test the inverted deferred was rejected - resolved observable inverted");
+	});
+
 	jQuery.when( 1 , errorDeferred , 3 ).done( function() {
 		ok( false , "Test the created deferred was rejected - rejected observable");
 	}).fail( function( error , errorParam ) {
 		strictEqual( error , "error" , "Test first param is first rejected value - rejected observable" );
 		strictEqual( errorParam , "errorParam" , "Test second param is second rejected value - rejected observable" );
 	});
+
+	jQuery.when( 1 , errorDeferred.invert() , 3 ).fail( function() {
+		ok( false , "Test the inverted deferred was resolved - rejected observable inverted");
+	}).done( function( a , b , c ) {
+		strictEqual( a , 1 , "Test first param is first resolved value - rejected observable inverted" );
+		same( b , [ "error", "errorParam" ] , "Test second param is second resolved value - rejected observable inverted" );
+		strictEqual( c , 3 , "Test third param is third resolved value - rejected observable inverted" );
+	});
 });
 
 test("jQuery.sub() - Static Methods", function(){